THE RED-BANDED THRIPS. 
27 
opment beiore changing to pupse, witli an average mean tempera- 
ture of about 71 ° F. (See Table III.) 
Table III. — Length of pre pupal stage of Heliothrips rubrocinctus in greenhouse at Wash- 
ington, D. C, April, 1912. 
Ex- 
peri- 
ment 
No. 
Date 
larva 
changed 
to 
prepupa. 
Number 
changed 
to 
prepupa. 
Date 
prepupa 
changed 
to pupa. 
Number 
changed 
to pupa. 
Minimum 
length of 
stage. 
Maximum 
length of 
stage. 
Average 
mean tem- 
perature. 
1 
2 
3 
4 
Apr. 11 
Apr. 13 
Apr. 12 
Apr. 13 
Apr. 11 
Apr. 12 
Apr. 15 
Apr. 16 
Apr. 17 
Apr. 20 
2 
1 
1 
2 
5 
o 
6 
3 
Apr. 12 
Apr. 15 
Apr. 16 
2 
1 
3 
Days 
Days. 
° F. 
71.5 
1 
3 
2 
4 
72.35 
Apr. 13 
Apr. 14 
Apr. 16 
Apr. 18 
Apr. 20 
Apr. 23 
3 
3 
5 
2 
1 
1 
1 ■ 
3 
2 
70. 75 
168 
i Approximate. 
A number of pupse in the greenhouse required from four to seven 
days for development, with an average mean temperature of from 
68° to 70° F. 
Table IV. — Length of pupal stage of Heliothrips rubrocinctus in greenhouse at Wash- 
ington, D. C, April, 1912. 
Ex- 
peri- 
ment 
No. 
Date 
prepupa 
changed 
to pupa. 
Number 
changed 
to pupa. 
Date 
pupa 
changed 
to adult. 
Number 
changed 
to adult. 
Minimum 
length of 
stage. 
Maximum 
length of 
stage. 
Average 
mean tem- 
perature. 
1 
2 
3 
4 
Apr. 12 
Apr. 13 
Apr. 13 
Apr. 15 
Apr. 22 
Apr. 20 
Apr. 16 
2 
3 
3 
3 
2 
1 
3 
/Apr. 16i 
\Apr. 162 
/Apr. 17 
\Apr. 18 
/Apr. 19 
\Apr. 20 
/Apr. 20 
)Apr. 20 
Apr. 27 
Apr. 24 
/Apr. 21 
\Apr. 22 
1 
1 
2 
1 
1 
2 
1 
2 
1 
1 
2 
1 
Days. 
Days. 
o p 
1 
4 
5 70.75 
68.5 
4 
6 
68.57 
69.37 
4 
6 
69.75 
7 
67.5 
1 
i 
1 9 a. m. 2 1 p. m. 
In Trinidad this thrips requires 12 days from the time the egg 
hatches until the adult appears, and with an estimated period of 
4 to 6 days for the egg stage the life cycle will be approximately 16 
to 18 days. Observations in a greenhouse at Washington, D.C., gave 
a total life cycle of 28 days as a minimum to 43 days as a maximum, 
with an average mean temperature of about 70° F. In Florida the 
life cycle may require only 20 days as a minimum, but during parts 
of the year at least will require in some cases 43 days for the com- 
plete life cycle and possibly even longer. This insect will probably 
have at least 10 generations annually in Florida. 
